1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Windfarm PowerMac thermal control.  MAX6690 sensor.
4 *
5 * Copyright (C) 2005 Paul Mackerras, IBM Corp. <paulus@samba.org>
6 */
7#include <linux/types.h>
8#include <linux/errno.h>
9#include <linux/kernel.h>
10#include <linux/init.h>
11#include <linux/slab.h>
12#include <linux/i2c.h>
13#include <asm/prom.h>
14#include <asm/pmac_low_i2c.h>
15
16#include "windfarm.h"
17
18#define VERSION "1.0"
19
20/* This currently only exports the external temperature sensor,
21   since that's all the control loops need. */
22
23/* Some MAX6690 register numbers */
24#define MAX6690_INTERNAL_TEMP	0
25#define MAX6690_EXTERNAL_TEMP	1
26
27struct wf_6690_sensor {
28	struct i2c_client	*i2c;
29	struct wf_sensor	sens;
30};
31
32#define wf_to_6690(x)	container_of((x), struct wf_6690_sensor, sens)
33
34static int wf_max6690_get(struct wf_sensor *sr, s32 *value)
35{
36	struct wf_6690_sensor *max = wf_to_6690(sr);
37	s32 data;
38
39	if (max->i2c == NULL)
40		return -ENODEV;
41
42	/* chip gets initialized by firmware */
43	data = i2c_smbus_read_byte_data(max->i2c, MAX6690_EXTERNAL_TEMP);
44	if (data < 0)
45		return data;
46	*value = data << 16;
47	return 0;
48}
49
50static void wf_max6690_release(struct wf_sensor *sr)
51{
52	struct wf_6690_sensor *max = wf_to_6690(sr);
53
54	kfree(max);
55}
56
57static const struct wf_sensor_ops wf_max6690_ops = {
58	.get_value	= wf_max6690_get,
59	.release	= wf_max6690_release,
60	.owner		= THIS_MODULE,
61};
62
63static int wf_max6690_probe(struct i2c_client *client,
64			    const struct i2c_device_id *id)
65{
66	const char *name, *loc;
67	struct wf_6690_sensor *max;
68	int rc;
69
70	loc = of_get_property(client->dev.of_node, "hwsensor-location", NULL);
71	if (!loc) {
72		dev_warn(&client->dev, "Missing hwsensor-location property!\n");
73		return -ENXIO;
74	}
75
76	/*
77	 * We only expose the external temperature register for
78	 * now as this is all we need for our control loops
79	 */
80	if (!strcmp(loc, "BACKSIDE") || !strcmp(loc, "SYS CTRLR AMBIENT"))
81		name = "backside-temp";
82	else if (!strcmp(loc, "NB Ambient"))
83		name = "north-bridge-temp";
84	else if (!strcmp(loc, "GPU Ambient"))
85		name = "gpu-temp";
86	else
87		return -ENXIO;
88
89	max = kzalloc(sizeof(struct wf_6690_sensor), GFP_KERNEL);
90	if (max == NULL) {
91		printk(KERN_ERR "windfarm: Couldn't create MAX6690 sensor: "
92		       "no memory\n");
93		return -ENOMEM;
94	}
95
96	max->i2c = client;
97	max->sens.name = name;
98	max->sens.ops = &wf_max6690_ops;
99	i2c_set_clientdata(client, max);
100
101	rc = wf_register_sensor(&max->sens);
102	if (rc)
103		kfree(max);
104	return rc;
105}
106
107static int wf_max6690_remove(struct i2c_client *client)
108{
109	struct wf_6690_sensor *max = i2c_get_clientdata(client);
110
111	max->i2c = NULL;
112	wf_unregister_sensor(&max->sens);
113
114	return 0;
115}
116
117static const struct i2c_device_id wf_max6690_id[] = {
118	{ "MAC,max6690", 0 },
119	{ }
120};
121MODULE_DEVICE_TABLE(i2c, wf_max6690_id);
122
123static const struct of_device_id wf_max6690_of_id[] = {
124	{ .compatible = "max6690", },
125	{ }
126};
127MODULE_DEVICE_TABLE(of, wf_max6690_of_id);
128
129static struct i2c_driver wf_max6690_driver = {
130	.driver = {
131		.name		= "wf_max6690",
132		.of_match_table = wf_max6690_of_id,
133	},
134	.probe		= wf_max6690_probe,
135	.remove		= wf_max6690_remove,
136	.id_table	= wf_max6690_id,
137};
138
139module_i2c_driver(wf_max6690_driver);
140
141MODULE_AUTHOR("Paul Mackerras <paulus@samba.org>");
142MODULE_DESCRIPTION("MAX6690 sensor objects for PowerMac thermal control");
143MODULE_LICENSE("GPL");
144